Vendor that allows you to display many sellable items (objects) and per item you can give a customer a notecard. The sell price is split amongst multiple authors. Set up is easy, since you have to enter the key of each author only once, and can reference any author by nick.

SecondLife mail client, released under GNU GPL licence. You can send and receive mail from within SecondLife both from and to other mail clients or external mail adresses. Has many command options and comes with an adjustable address book that allows to enter addresses and address groups.